In the life of most wells the reservoir pressure decreases over time resulting in the failure of the well to produce fluids utilizing the formation pressure solely. As the formation pressure decreases, the well tends to fill up with liquids, such as oil and water, which inhibits the flow of gas into the wellbore and may prevent the production of liquids. It is common to remove this accumulation of liquid by artificial lift systems such as plunger lift, gas lift, pump lifting and surfactant lift wherein the liquid column is blown out of the well utilizing the reaction between surfactants and the liquid.
One method of producing fluids from a declining well having gas production is by utilizing a plunger lift system. A well is shut-in allowing a plunger to fall through the fluid column to the bottom of the well. When gas pressure from the formation is sufficient, the well may be opened allowing the gas to lift the plunger and the fluid above the plunger to the surface for production. The plunger acts as an interface between the gas and liquid in the well. However, when gas pressure is overcome by the hydrostatic head in the well, well production will cease.
Wells that are candidates for plunger lift are already very susceptible to being killed. These wells are commonly killed by allowing excessive liquid to accumulate in the well. Fluid may accumulate from allowing the well to remain flowing for too great a period of time or wiping fluid from the interior of the tubing, or both. The margin of error for maintaining production is further decreased as the well declines and the gas volume produced at the formation decreases.
Typical plunger lift systems require a well that produces a substantial quantity of gas. Therefore, there is a need for a plunger lift system that facilitates continued production of declining wells with decreasing produced gas volumes and gas pressures.